> ## Documentation Index
> Fetch the complete documentation index at: https://docs.uptimekit.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Time-series Storage

> Configure TimescaleDB or ClickHouse for monitor events and uptime history

UptimeKit stores monitor events, status changes, and latency history in a time-series backend. You can use TimescaleDB with PostgreSQL or ClickHouse as a separate database.

## Overview

UptimeKit supports two time-series backends:

* **TimescaleDB**: Store time-series data in PostgreSQL with the TimescaleDB extension
* **ClickHouse**: Store time-series data in a dedicated ClickHouse database

Choose the backend with the `TIMESERIES_BACKEND` environment variable.

## TimescaleDB (Recommended)

TimescaleDB can use your main application database or a separate database since its just a PostgreSQL extension.

### Main Database

If your main PostgreSQL database has the TimescaleDB extension available, UptimeKit can reuse `DATABASE_URL`.

```bash theme={null}
DATABASE_URL=postgresql://postgres:postgres@localhost:5432/uptimekit
TIMESERIES_BACKEND=timescale
```

### Separate Database

If you want time-series data in a different TimescaleDB database, set `TIMESCALE_DATABASE_URL`.

```bash theme={null}
DATABASE_URL=postgresql://postgres:postgres@localhost:5432/uptimekit
TIMESERIES_BACKEND=timescale
TIMESCALE_DATABASE_URL=postgresql://postgres:postgres@localhost:5432/uptimekit_timeseries
```

<Info>
  If `TIMESCALE_DATABASE_URL` is not set, UptimeKit uses `DATABASE_URL` for
  TimescaleDB.
</Info>

<Warning>
  The PostgreSQL database used for time-series data must have the TimescaleDB
  extension installed.
</Warning>

## ClickHouse

ClickHouse can also be used as the time-series backend by setting the ClickHouse environment variables.

```bash theme={null}
TIMESERIES_BACKEND=clickhouse
CLICKHOUSE_URL=http://localhost:8123
CLICKHOUSE_USER=default
CLICKHOUSE_PASSWORD=
```

<Info>
  Set these variables for each UptimeKit app that reads or writes monitor
  history.
</Info>

## Environment Variables

| Variable                 | Required       | Description                                             |
| ------------------------ | -------------- | ------------------------------------------------------- |
| `TIMESERIES_BACKEND`     | No             | Use `timescale` or `clickhouse` defaults to `timescale` |
| `DATABASE_URL`           | Yes            | Main PostgreSQL database URL                            |
| `TIMESCALE_DATABASE_URL` | No             | Optional TimescaleDB URL for time-series data           |
| `CLICKHOUSE_URL`         | For ClickHouse | ClickHouse HTTP endpoint                                |
| `CLICKHOUSE_USER`        | For ClickHouse | ClickHouse username                                     |
| `CLICKHOUSE_PASSWORD`    | For ClickHouse | ClickHouse password                                     |